project manager for what?
For engineering companies, you are not going to find a PM with a degree in business....
As for what they do....
they manage the projects, make sure budgets are aligned, and makes sure everything is going efficiently. Sounds easy, but as with everything else in life, it's easier said than done.
Travel? Depends on the company. If it is client based, yeah, you will travel alot.
Job Security...it depends, do you suck at the job?
Contract based? I hope not. If it was, then there would be no incentive for the PM to follow through.